| 摘要 |
PURPOSE:To detect directly the position of an optical track and to prevent the time delay between detection signals by constituting a device with a means, which separates a converged radiated light to two beams which can be separated from each other by natural characteristics, and a means which detects intensities of separated beams independently of each other and generating an error signal of position related to detection signals. CONSTITUTION:A laser light source 12 inclines the plane of polarization of a luminous flux at about 45 deg. to the horizontal. The luminous flux 100 is irradiated to a double refracting prism 13, and horizontally polarized components are refracted at an angle different from that of vertically polarized components. Luminous fluxes 101 and 102 which are emitted from the prism 13 and are separated from each other with respect to angle are shown in the figure D. These luminous fluxes polarized at right angles form focused light spots 40 and 41 individually on the surface of a disc 11 as they are. A pit 44 passes focused light spots 40 and 41 by the rotation of the disc 11. Luminous fluxes 101 and 102 are modulated when they are reflected from the disc 11, and they are deviated from the axis of a lens by a splitter 4 after being returned. Reflected luminous fluxes 101 and 102 are reflected by a polarizing beam splitter 6 and are converged onto photodetectors 8 and 9 respectively.
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